Russian President Vladimir Putin has pledged to respond to NATO's expansion toward Russia's borders amid tensions with the Western alliance over the ongoing crisis in Ukraine.

Putin made the remarks on Tuesday at an emergency meeting of the Security Council of the Russian Federation in Moscow.

“We shall provide an adequate and well-measured response to NATO’s expansion towards Russia’s borders, and we shall take note of [the West] setting up a global missile defense architecture and building up its arsenals of precision-guided weapons,” said Putin, adding that the Western military alliance is “blatantly building up its forces in Eastern Europe, including the Black Sea and the Baltic Sea areas.”

According to Putin, NATO military buildup near Russia's borders is not just for defense as the Western alliance claims, but is “an offensive weapon” and “element of the US offensive system deployed outside the mainland.”

Furthermore, Putin called for the implementation of all planned measures “to strengthen" Russia's "defense capabilities, including plans for Crimea and Sevastopol.”

This comes as NATO has held a number of war games in Eastern Europe after Ukraine’s Autonomous Republic of Crimea integrated into the Russian Federation following a referendum in March.

NATO has also reinforced its air patrol over the Baltic region, with radar-equipped aircraft making regular flights over the territories of Poland and Romania.

Last month, the Western military alliance held military drills near Russia’s western border. Nearly 5,000 troops and 800 military vehicles from 10 NATO member states, including the US, Britain and Canada participated in the war games near the Latvian capital, Riga.

Russia sees the Western military alliance’s moves as a sign of aggression amid the crisis in Ukraine.